The invention is related to a circuit arrangement to detect knocking in an internal combustion engine, and particularly, to a circuit arrangement having a knock sensor which is connected with an evaluating circuit via a filter effecting a separation of the knock frequency.
In automotive engineering, knocking in an internal combustion engine is a dangerous operating state which can lead to damage in the long run. Therefore, circuit arrangements to detect knocking in an internal combustion engine are known which determine the frequency spectrum of the internal combustion engine by means of a knock sensor and, after filtering out the relevant knock frequency, feed it to a circuit arrangement which, when knocking is detected, changes the operating parameters of the internal combustion engine in such a way that knock-proof operation is brought about. Increasingly greater demands are made with respect to the detecting and evaluating devices of the known circuit arrangements. For example, increasingly higher knock frequencies must be determined and evaluated as a result of modern internal combustion engine construction. This conflicts with the relatively low limit frequencies of the evaluating circuits presently in use. In addition, there is a demand for arrangements for evaluating the knock sensor signals which are constructed in a particularly simple manner.